Introduction

  • Fluids refers to gas or liquid.

  • Liquid — takes the shape of container and has a free surface. Gas — occupies the entire container, and has no free surface.

  • Liquid — hard to compress; Gas — easy to compress. Liquids are called incompressible fluids; gases are called compressible fluids.

  • A ‘vapor’ is a gas whose temperature and pressure are much nearer to its liquid phase. Thus steam is considered a vapor because its state is normally not far from that of water. A ‘gas’ may be defined as a highly superheated vapor; that is, its state is far away from the liquid phase. Thus air is considered a gas because its state is normally very far from that of liquid-air.

  • Fluid Mechanics deals with behavior of fluids at rest (fluid statics) or in motion (fluid dynamics).